Organic semiconductor thin films using aromatic enediyne derivatives and manufacturing methods thereof, and electronic devices incorporating such films

ABSTRACT

Disclosed are organic semiconductor thin films using aromatic enediyne derivatives, manufacturing methods thereof, and methods of fabricating electronic devices incorporating such organic semiconductor thin films. Aromatic enediyne derivatives according to example embodiments provide improved chemical and/or electrical stability which may improve the reliability of the resulting semiconductor devices. Aromatic enediyne derivatives according to example embodiments may also be suitable for deposition on various substrates via solution-based processes, for example, spin coating, at temperatures at or near room temperature to form a coating film that is then heated to form an organic semiconductor thin film. The availability of this reduced temperature processing allows the use of the aromatic enediynes derivatives on large substrate surfaces and/or on substrates not suitable for higher temperature processing. Accordingly, the organic semiconductor thin films according to example embodiments may be incorporated in thin film transistors, electroluminescent devices, solar cells, and memory devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Divisional Application of, and claims priority under 35 U.S.C.§120 to, U.S. application Ser. No. 11/583,085, filed Oct. 19, 2006 U.S.Pat. No. 7,534,899, the entire contents of which are incorporated hereinby reference.

BACKGROUND

1. Technical Field

Example embodiments relate to aromatic enediyne derivatives, organicsemiconductor thin films formed using such aromatic enediyne derivativesand methods of manufacturing such films, and electronic devicesincorporating such organic semiconductor thin films and methods ofmanufacturing such devices, and, for example, to organic semiconductorthin films fabricated from such aromatic enediyne derivatives thatexhibit improved chemical and electrical stability. The aromaticenediyne derivatives according to example embodiments may be applied tosubstrates via solution-based processes, for example, spin coating, andare suitable for application at or near room temperature to form acoating layer that, after thermal treatment, may form an organicsemiconductor thin film on the substrate that may be used in forming acarrier transport layer in an electronic device incorporating such anorganic semiconductor thin film.

2. Description of the Related Art

In general, flat display devices, for example, liquid crystal displaydevices or organic electroluminescent display devices, utilize variousthin film transistors during operation. One basic thin film transistorconstruction comprises a gate electrode formed on a gate dielectric,source/drain electrodes, and a semiconducting channel region formed in asemiconducting material adjacent the gate dielectric and opposite thegate electrode. The conductivity of this semiconducting channel regionis, in turn, controlled through operation of the gate electrode. Thep-type or n-type semiconductor material forming the channel regionserves as a conductive material when the gate electrode is in an “on”state to allow current to flow between the source and drain electrodesand serves as a resistive material when the gate electrode is in an“off” state to suppress leakage current between the source and drainelectrodes. The “on” and “off” states of the transistor may correspondto two different voltages that may be alternatively applied to the gateelectrode for controlling current flow between the source and drainelectrodes.

Although a range of semiconductor materials may be used for forming thinfilm transistors, amorphous Si (a-Si) and polycrystalline Si (poly-Si)are widely used. As a result of recent trends toward larger areas, lowerprices and/or improved flexibility of video displays, various effortshave been directed to manufacturing semiconductors using more flexibleorganic materials rather than the conventional, relatively expensiveand/or rigid inorganic materials, which may require the use ofhigher-temperature vacuum and/or furnace processes in their formation.

Research into various lower molecular weight organic materials, forexample, pentacene, for forming organic semiconductor films is presentlyongoing. In this regard, the lower molecular weight organic materials,for example, pentacene, have been reported as having charge mobility inthe range of 3.2 to 5.0 cm²/V-s or more and an excellent current on/offratio. These materials, however, are known to have deficienciesincluding, for example, the expense associated with forming layers ofsuch materials and difficulty forming a generally uniform layer acrosslarge areas of a substrate. These deficiencies are, to some degree,attributable to the need to use expensive vacuum deposition apparatus informing thin films from these lower molecular weight organic materialsand an associated difficulty in forming fine patterns.

Further, oligomeric organic semiconductors, for example, a solublepentacene precursor, have been reported as suitable for application to asubstrate and annealing at about 120 to 200° C. to produce an organicsemiconducting layer having a charge mobility of about 0.1 cm²/V-s. Inaddition, other oligothiophene precursors capable of being applied to asubstrate to produce an organic semiconducting layer having a chargemobility of 0.03 to 0.05 cm²/V-s and capable of being annealed at 180 to200° C., have also been reported. However, such organic semiconductorsmay be chemically unstable during the subsequent processing necessary tocomplete the fabrication of a semiconductor device and are accordinglydifficult to implement in an actual device manufacturing line. Moreover,results obtained by repeated current-electron sweeping for evaluatingelectrical stability tends to exhibit a lack of electrical stabilitythat may result in both reduced gate threshold voltage, increasedleakage currents and/or reduced reliability of the resulting devices.

Other organic compounds containing an acetylene groups and methods ofmanufacturing a thin film of such materials through a vacuum depositionprocess using the organic compound have also been reported. However, theorganic compounds and the methods of manufacturing thin films from suchorganic compounds may require a vacuum deposition process in order tomanufacture a thin film. Accordingly, the use of lower molecular weightcompounds, for example, pentacene, may be expensive and generallyunsuited for preparing organic semiconductor films over a largesubstrate area for cost-sensitive products.

SUMMARY

Accordingly, aromatic enediyne derivatives have been developed toaddress one or more deficiencies that have been identified in theconventional art. Compounds according to example embodiments comprise agroup of aromatic enediyne derivatives that may be utilized insolution-based application processes, for example, spin coating at roomtemperature, in order to apply the aromatic enediyne derivative(s) to avariety of substrates to form a coating film. These coating films, whichcontain one or more of the aromatic enediyne derivatives according toexample embodiments, may then be converted into organic semiconductorthin films exhibiting improved chemical and/or electrical stabilitysuitable for fabricating devices having improved functionality and/orreliability.

Example embodiments may also include precursor solutions comprising oneor more of the aromatic enediyne derivatives and an organic solvent ororganic solvent system useful in the manufacture of organicsemiconductor films and devices that incorporate such films.

Example embodiments may also include methods of manufacturing organicsemiconductor thin films using a precursor solution incorporating one ormore aromatic enediyne derivatives and an organic solvent or solventsystem. These precursor solutions may, in turn, be used for formingorganic semiconductor thin films.

Example embodiments may also include methods for incorporating organicsemiconductor thin films into semiconductor devices in order to produceelectronic devices which utilize the organic semiconductor thin film asa carrier transport layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the aromatic enediyne derivatives, organicsemiconductor layers formed from the aromatic enediyne derivatives,active structures incorporating such organic semiconductor layers andsemiconductor devices incorporating such active structures are addressedmore fully below with reference to the attached drawings in which:

FIG. 1 is a graph showing the result of differential scanningcalorimetry (DSC) of an example embodiment of an aromatic enediynederivative as synthesized in Preparative Example 1 below;

FIG. 2 is a graph showing the result of DSC of an example embodiment ofan aromatic enediyne derivative as synthesized in Preparative Example 2below;

FIG. 3 is a graph showing the result of DSC of an example embodiment ofan aromatic enediyne derivative as synthesized in Preparative Example 3below;

FIG. 4 is a graph showing the result of DSC of an example embodiment ofan aromatic enediyne derivative as synthesized in Preparative Example 4below;

FIG. 5 is a graph showing the result of a thermogravimetry analysis(TGA) of an example embodiment of an aromatic enediyne derivative assynthesized in Preparative Example 1 below;

FIG. 6 is a graph showing the result of TGA of an example embodiment ofan aromatic enediyne derivative as synthesized in Preparative Example 2below;

FIG. 7 is an IR spectrum of an example embodiment of an organicsemiconductor thin film as manufactured in Example 1 below; and

FIG. 8 is a schematic cross-sectional view showing an example embodimentof an organic thin film transistor.

It should be noted that these Figures are intended to illustrate thegeneral characteristics of organic semiconductor compounds andsemiconductor device structures according to example embodiments tosupplement the written description provided below. These drawings,however, are not necessarily to scale and may not precisely reflect thecharacteristics of any given embodiment, and should not be interpretedas defining or limiting the range of values or properties of embodimentswithin the scope of the claims. In particular, the relative positioningand sizing of atoms, bonds, layers or regions may be reduced orexaggerated for clarity.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various example embodiments of the present invention will now bedescribed more fully with reference to the accompanying drawings inwhich some example embodiments of the invention are shown. In thedrawings, the thicknesses of layers and regions may be exaggerated forclarity.

Detailed illustrative embodiments of the present invention are disclosedherein. However, specific structural and functional details disclosedherein are merely representative for purposes of describing exampleembodiments of the present invention. This invention may, however, maybe embodied in many alternate forms and should not be construed aslimited to only the embodiments set forth herein.

Accordingly, while example embodiments of the invention are capable ofvarious modifications and alternative forms, embodiments thereof areshown by way of example in the drawings and will herein be described indetail. It should be understood, however, that there is no intent tolimit example embodiments of the invention to the particular formsdisclosed, but on the contrary, example embodiments of the invention areto cover all modifications, equivalents, and alternatives falling withinthe scope of the invention. Like numbers refer to like elementsthroughout the description of the figures.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments of thepresent invention. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between”, “adjacent” versus “directlyadjacent”, etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments of the invention. As used herein, the singular forms “a”,“an” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise. It will be further understoodthat the terms “comprises”, “comprising,”, “includes” and/or“including”, when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the FIGS. Forexample, two FIGS. shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Also, the use of the words “compound,” “compounds,” or “compound(s),”refer to either a single compound or to a plurality of compounds. Thesewords are used to denote one or more compounds but may also justindicate a single compound.

Now, in order to more specifically describe example embodiments of thepresent invention, various embodiments of the present invention will bedescribed in detail with reference to the attached drawings. In thefigures, if a layer is formed on another layer or a substrate, it meansthat the layer is directly formed on another layer or a substrate, orthat a third layer is interposed therebetween. In the followingdescription, the same reference numerals denote the same elements.

Although example embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

Aromatic enediyne derivatives encompassed by example embodiments may berepresented by any one of Formulas I to III below:

wherein, in Formulas I to III,

X₁, X₂, X₃, X₄, X₅, X₆, A₁, and A₂ are each independently selected fromthe group consisting of unsubstituted and unsubstituted C3-C30 arylenegroups, and unsubstituted and substituted C2-C30 heteroarylene groups,

R₁, R₂, R₃, R₄, R₅, and R₆ are each independently selected from thegroup consisting of hydrogen, halogen elements, a nitro group, an aminogroup, a cyano group, —SiR¹R²R³ (wherein R¹, R², and R³ are eachindependently selected from a group consisting of hydrogen and C1-C10alkyl groups), unsubstituted and substituted C1-C20 alkyl groups,unsubstituted and substituted C2-C20 alkenyl group, unsubstituted andsubstituted C2-C20 alkynyl groups, unsubstituted and substituted C1-C20alkoxy groups, unsubstituted and substituted C6-C20 arylalkyl groups,unsubstituted and substituted C6-C30 aryloxy groups, unsubstituted andsubstituted C2-C30 heteroaryloxy groups, unsubstituted and substitutedC1-C20 heteroalkyl groups, and unsubstituted and substituted C2-C30heteroarylalkyl groups (in which none of R₁, R₂, R₃, and R₄ are hydrogenin Formula I, neither R₅ and R₆ are hydrogen in Formula II, and neitherR₃ and R₄ are hydrogen in Formula III), and

a, b, c, d, e, and fare each independently an integer from 0 to 10inclusive, and further wherein the expressions (a+b+c)>0 and, ifapplicable, (d+e+f)>0, are both satisfied.

A plastic substrate, for example, those used in fabricating flexibledisplay devices, may not endure a heat-curing temperature greater than150° C., thus causing problems related to light weight and/orflexibility. Lower molecular weight aromatic enediyne derivativesaccording to example embodiments may form an organic semiconductormaterial having linear conjugated chains, which may be used tomanufacture an organic semiconductor thin film. Further, exampleembodiments of organic semiconductor materials use a solution-basedprocess at lower temperatures, leading to an organic semiconductor thinfilm having regular molecular arrangement of the lower molecularsemiconductor material and electrical stability of the polymer.

In aromatic enediyne derivatives according to example embodiments, twoacetylene groups may be bound to a double bond of an aromaticsubstituent to form an unsaturated core. Thus, the aromatic enediynederivative may be advantageous because it has a specific chemicalstructure and active mechanism making it suitable for realizing higherreactivity, and thus a radical benzene ring may be more easily formedeven at lower temperatures, thereby realizing polymerization throughintermolecular bonding.

In the aromatic enediyne derivatives of Formulas I to III, X₁, X₂, X₃,X₄, X₅, X₆, A₁, and A₂, may each be independently selected from thegroups represented by the formulae illustrated below. The carriermobility in the resulting organic semiconductor layer appears to be afunction of the thiophene and/or phenyl groups in order to increase themobility of a semiconductor.

The X₁, X₂, X₃, A₁, and A₂ in Formula I may include at least twothiophene rings.

(in which the A₁ and A₂ in Formula I are not

(1,3,4-thiadiazole)).

Specifically, example embodiments of aromatic enediyne derivativesinclude those compounds represented below in Formula V and Formula VI:

in Formulas V and VI, R is selected from the group consisting of halogenelements, a nitro group, an amino group, a cyano group, —SiR¹R²R³ (whereR¹, R², and R³ are each independently selected from a group consistingof hydrogen and C1-C10 alkyl groups), unsubstituted and substitutedC1-C20 alkyl groups, unsubstituted and substituted C2-C20 alkenylgroups, unsubstituted and substituted C2-C20 alkynyl groups,unsubstituted and substituted C1-C20 alkoxy groups, unsubstituted andsubstituted C6-C20 arylalkyl groups, unsubstituted and substitutedC6-C30 aryloxy groups, unsubstituted and substituted C2-C30heteroaryloxy groups, unsubstituted and substituted C1-C20 heteroalkylgroups, and unsubstituted and substituted C2-C30 heteroarylalkyl groups,and m and n are each an integer from 1 to 10 inclusive.

More specifically, example embodiments of aromatic enediyne derivativesinclude compounds corresponding to Formulas VII to X below:

Aromatic enediyne derivatives according to example embodiments may beformed using any suitable synthesis process(es) and are not limited bythe manner in which they are formed.

One or more such aromatic enediyne derivatives may be used as materialfor forming an organic semiconductor active layer and thus may beeffectively incorporated in the fabrication of various electronicdevices, for example, thin film transistors, electroluminescent devices,solar cells, and memory devices.

In addition, example embodiments provide for precursor solutions thatmay be used in the fabrication of an organic semiconductor, comprisingone or more aromatic enediyne derivatives and an organic solvent ororganic solvent system.

In a precursor solution, an aromatic enediyne derivative may be used inthe form of a combination of two or more of aromatic enediynederivatives represented by Formulas I to III. Further, the aromaticenediyne derivative(s) incorporated in the precursor solution may bepresent in an amount of 0.01 to 30 wt % based on the total weight of thesolution.

An organic solvent or solvent system used in forming a precursorsolution may include at least one solvent selected from a groupconsisting of aliphatic hydrocarbon solvents, for example, hexane andheptane; aromatic hydrocarbon solvents, for example, toluene, pyridine,quinoline, anisol, mesitylene and xylene; ketone-based solvents, forexample, methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, cyclohexanoneor acetone; ether-based solvents, for example, tetrahydrofuran orisopropyl ether, acetate-based solvents, for example, ethyl acetate,butyl acetate or propylene glycol methyl ether acetate; alcohol-basedsolvents, for example, isopropyl alcohol or butyl alcohol; amide-basedsolvents, for example, dimethylacetamide or dimethylformamide;silicon-based solvents, and mixtures thereof.

In addition, example embodiments may include methods of manufacturingorganic semiconductor thin films, comprising i) applying a precursorsolution to a substrate to form a coating film; and ii) heating thecoating film to a treatment temperature and for a time period sufficientto initiate crosslinking of aromatic enediyne derivative(s), thusforming a thin film.

The substrate on which the organic semiconductor thin film is formed isnot particularly limited so long as it does not interfere with theintended use or processing of aromatic enediyne derivatives or theprecursor solutions incorporating such derivatives, and may, forexample, be selected from a group including glass substrates, siliconwafers, ITO glass, quartz, a silica-coated substrates, alumina-coatedsubstrates, plastic substrates, etc., depending on the demands andrequirements of the intended end use for the resulting devices.

Useful processes for applying the precursor solution to the substratefor form a coating film include spin coating, dip coating, roll-to-rollcoating, screen coating, spray coating, spin casting, flow coating,screen printing, inkjet coating and drop casting. Of these coatingprocesses, it is anticipated that spin coating processes may be easilyintegrated into a semiconductor fabrication process and is capable ofproducing sufficiently uniform coating layers over large substrateareas. The actual sequences utilized in such spin coating processes mayvary somewhat, but it is anticipated that spin coating processesutilizing a spin speed in the range from 100 to 10,000 rpm will becapable of producing acceptable coating films on most substrates.

Subsequently, the coating film may be subjected to a thermal treatmentto promote crosslinking and the polymerization of aromatic enediynederivative(s) contained therein, thereby obtaining a desired organicsemiconductor thin film. Depending on the substrate material and theparticular aromatic enediyne derivative(s) and organic solvent(s)utilized in a particular application, the thermal treatment may beconducted at a treatment temperature of 100 to 250° C.

The duration of the thermal treatment may range from 1 to 100 minutesand may be conducted under a generally uniform temperature or may beconducted under varying temperatures, for example, with the treatmenttemperature gradually increasing over the duration of the thermaltreatment or with more complex temperature profiles including, forexample, a temperature ramp up, followed by a hold period, followed by atemperature ramp down. As will be appreciated by those skilled in theart, the pressure and gas content to which the coating film is exposedduring the thermal treatment may also be varied throughout the course ofthe treatment to provide, for example, increased solvent removal duringthe early portions of the treatment and suppressed oxidation during thelater portions of the treatment through the varied application of vacuumand the use of one or more inert or less reactive gases.

The crosslinking mechanism of aromatic enediyne derivatives isrepresented by the Reaction 1 illustrated below:

As is apparent from Reaction 1, the acetylene groups bound to the doublebonds of an aromatic enediyne derivative are formed into radical benzenerings at a predetermined or desired reaction temperature thanks tohigher reactivity of the active mechanism of enediyne, resulting in apolymer network through intermolecular bonding.

In the case where a semiconductor thin film is formed using aconventional precursor solution, the thin film may crack due to theemission of gas created by the intermolecular bonding or solvent duringthe heat treatment. However, the organic semiconductor thin filmaccording to example embodiments is polymerized through the radicalreaction using the higher reactivity of the active mechanism ofenediyne, thereby reducing or preventing the cracking of the thin film,which may be caused by the generation of gas during a continuousprocess. Moreover, the crosslinking reaction progresses without the useof an additive, thus reducing or preventing a negative effect capable ofinterrupting the molecular arrangement due to the use of the additiveacting as an impurity.

The organic semiconductor thus formed may maintain improved transistorproperties due to intermolecular packing based on the regulararrangement of a monomolecular aromatic enediyne derivative andintermolecular cross-network formation, and may also assure chemical andelectrical stability and reliability upon formation into a polymericthin film. In the case where the organic semiconductor is applied as thecarrier transport layer to electronic devices, improved properties maybe provided and the cost reduction effect may be improved or maximizedby adopting a room-temperature solution-based process.

Specific examples of the electronic device that may include organicsemiconductor regions formed from aromatic enediyne derivatives includeorganic thin film transistors, electroluminescent devices, solar cells,and memory devices. Aromatic enediyne derivatives according to exampleembodiments may be applied as a solution or precursor composition tosubstrates used in forming these or other devices using conventionalcoating processes.

A better understanding of example embodiments may be obtained in lightof the following examples which are set forth to illustrate, but shouldnot to be construed to limit, the disclosure.

Preparative Example 1 Synthesis of Example Aromatic Enediyne DerivativeA

2 ml (18.0 mmol) of 2,3-dibromothiophene, commercially available fromAldrich under the Product No. D4,390-5, and 3.5 ml (27.0 mmol) of1-heptyne, commercially available from Aldrich under the Product No.24,4414, were mixed with a solvent of tetrahydrofuran/diisopropylamine(1:1), and 0.23 g (0.36 mmol) of palladium dichlorodiphosphine, 70 mg(0.36 mmol) of copper iodide and 0.1 g (0.36 mmol) of triphenylphosphinewere sequentially added thereto. The reaction solution was heated at 70°C. for 8 hours, and washed with an aqueous solution of ammoniumchloride. The resulting organic layer was dried over magnesium sulfate,dried under reduced pressure, and purified using silica gel columnchromatography, thus obtaining 4.6 g of 2-heptynyl 3-bromothiophene. Thecompound thus obtained was added with 3.3 ml (23.2 mmol) oftrimethylsilylacetylene, commercially available from Aldrich under theProduct No. 21,817-0, and then subjected to the above synthesis process,to prepare 2.7 g (9.84 mmol) of2-heptynyl-3-trimethylsilylethynylthiophene, which was then mixed with12.8 ml (12.8 mmol) of lithium diisopropylamide (1 M) at about −78° C.The reaction mixture was stirred at the same temperature for 30 minutes,then combined with 2.4 ml (11.8 mmol) of2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-oxaborolane, commerciallyavailable from Aldrich under the Product No. 41,714-9, and allowed toreact in a bath while the temperature was increased to room temperature.The resultant reaction solution was poured into an aqueous solution of 1N HCl, treated with chloroform to obtain an organic layer, which wasthen dried over magnesium sulfate 1 N HCl, treated with chloroform toobtain an organic layer, which was then dried over magnesium sulfate anddistilled under reduced pressure, thus obtaining 4.1 g of a compound ain an oil phase. Analysis of the compound 1a produced the following NMRdata: ¹H NMR (300 MHz, CDCl₃), δ(ppm) 0.24 (s, 9), 0.92 (t, 3H, J=7.2Hz), 1.24-1.64 (m, 18), 2.49 (t, 2H, J=7.0 Hz), 7.47 (s, 1H).

0.5 g (1.54 mmol) of 2,2′-dibromo-5,5′-bithiophene and 1.6 g (4.00 mmol)of borolane 1a were added to toluene and water, and then aPd(PPh₃)₄[(tetrakis(triphenylphosphine) palladium)(0)(Aldrich)] catalystand potassium carbonate were added thereto, after which the reactionmixture was allowed to react at 110° C. for 8 hours and then washed withan aqueous solution of 1 N HCl. The resulting organic layer was driedand purified using silica gel column chromatography, thus obtaining 0.64g (58%) of a compound 2a. Analysis of the compound 2a produced thefollowing NMR data: ¹H NMR (300 MHz, CDCl₃), δ(ppm) 0.26 (s, 18H), 0.93(t, 6H, J=7.2 Hz), 1.24-1.67 (m, 1211), 2.50 (t, 4H, J=7.0 Hz), 7.05 (d,4H, J=2.8 Hz), 7.34 (s, 2H)

0.54 g of the compound 2a was dissolved in chloroform/methylalcohol(having a volume ratio of 1/3) and then added with 1 g of NaOH, and thereaction mixture was stirred for 10 min. The stirred reaction solutionwas washed with an aqueous solution of 1 N HCl, and the organic layerwas dried and purified using silica gel column chromatography, thusyielding 0.3 g of the derivative A. Analysis of the derivative Amaterial produced the following NMR data: ¹H NMR (300 MHz, CDCl₃), δ(ppm) 0.93 (t, 6H, J=7.1 Hz), 1.35-1.67 (m, 12H), 2.51 (t, 4H, J=7.0Hz), 3.26 (s, 2H), 7.05-7.07 (m, 6H).

Preparative Example 2 Synthesis of Example Aromatic Enediyne DerivativeB

0.25 g (1 mmol) of 2,2′:5′,2″-terthiophene, commercially available fromAldrich under the Product No. 31,107-3, was added to chloroform, and0.35 g (2.0 mmol) of N-bromosuccinimide was added thereto, thusobtaining dibromide 1b, which was then subjected to Suzuki coupling anddesilylation under the same synthetic conditions as in the synthesis ofthe derivative A, thereby yielding the derivative B. Analysis of thederivative B produced the following NMR data. ¹H NMR (300 MHz, CDCl₃), δ(ppm) 0.93 (t, 6H, J=7.2 Hz), 1.24-1.67 (m, 12H), 2.51 (t, 4H, J=7.0Hz), 3.26 (s, 2H), 7.05-7.08 (m, 8H).

Preparative Example 3 Synthesis of Example Aromatic Enediyne DerivativeC

5,5′-bromo-2,2′-bithiophene, commercially available from Aldrich underthe Product No. 51,549-3, and 2-thiopheneboronic acid, commerciallyavailable from Aldrich under the Product No. 43,683-6, were subjected toSuzuki coupling, thus obtaining a predetermined or desired product,which was then added with N-bromosuccinimide to preparedibromotetrathiophene 1c. Subsequently, the compound 1c was subjected toSuzuki coupling and desilylation under the same synthetic conditions asin the synthesis of the derivative A, therefore yielding the derivativeC. Analysis of the derivative C produced the following NMR data ¹H NMR(300 MD, CDCl₃), δ (ppm) 0.93 (t, 6H, J=7.2 Hz), 1.24-1.67 (m, 12H),2.51 (t, 4H, J=7.0 Hz), 3.27 (s, 2H), 7.05-7.09 (m, 10H).

Preparative Example 4 Synthesis of Example Aromatic Enediyne DerivativeD

1 g (4.2 mmol) of 1,4-dibromobenzene, commercially available fromAldrich under the Product No. D3,902-9, was subjected to Suzuki couplingwith 2-bromothiophene, to prepare 0.72 g (3.0 mmol) of a predeterminedor desired product, which was then added to chloroform, and 1.1 g (6.2mmol) of N-bromosuccinimide was added thereto, thus preparing 0.6 g ofdibromide 1d. Subsequently, the compound 1d was subjected to Suzukicoupling and desilylation under the same synthetic conditions as in thesynthesis of the derivative A, therefore yielding the derivative D.Analysis of the derivative D produced the following NMR data: ¹H NMR(300 MHz, CDCl₃), δ(ppm) 0.93 (t, 6H, J=7.2 Hz), 1.24-1.67 (m, 12H),2.51 (t, 4H, J=7.0 Hz), 3.27 (s, 2H), 7.01 (s, 2H), 7.13 (d, 2H, J=3.8Hz), 7.25 (d, 2H, J=3.8 Hz), 7.60 (s, 4H).

Preparative Example 5 Synthesis of Example Aromatic Enediyne DerivativeIIc

2.5 ml (22.6 mmol) of 3,4-dibromothiophene, commercially available fromAldrich under the Product No. 24,715-4, and 8 ml (56.5 mmol) oftrimethylsilylacetylene were mixed with a solvent oftetrahydrofuran/diisopropylamine (1:1), and 0.15 g (0.23 mmol) ofpalladium dichlorodiphosphine, 21 mg (0.11 mmol) of copper iodide and0.1 g (0.36 mmol) of triphenylphosphine were then sequentially addedthereto. The reaction solution was heated at 70° C. for 8 hours, andwashed with an aqueous solution of ammonium chloride. The resultingorganic layer was dried over magnesium sulfate, dried under reducedpressure, and purified using silica gel column chromatography, thusobtaining 1.5 g of 3,4-bis(trimethylsilylethynyl)thiophene (IIa).

1 g (3.62 mmol) of 3,4-bis(trimethylsilylethynyl)thiophene, which wasthen mixed with 10.8 ml (10.8 mmol) of lithium diisopropylamine (LDA) (1M) at about −78° C. The reaction mixture was stirred at the sametemperature for 30 minutes, then combined with 2.4 ml (11.8 mmol) of2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-ioxaborolane, commerciallyavailable from Aldrich under the Product No. 41,714-9, and allowed toreact in a bath while the temperature was increased to room temperature.The resultant reaction solution was poured into an aqueous solution of 1N HCl, treated with chloroform to obtain an organic layer, which wasthen dried over magnesium sulfate 1 N HCl, treated with chloroform toobtain an organic layer, which was then dried over magnesium sulfate anddistilled under reduced pressure, thus obtaining 2.1 g of a compounddiborolane in an oil phase.

2.96 g (9.0 mmol) of 2-bromo-2′-hexyl-5,5′-bithiophene and 2.1 g (4.0mmol) of borolane were added to toluene and water, and then aPd(PPh₃)₄[(tetrakis(triphenylphosphine) palladium)(0)(Aldrich)] catalystand potassium carbonate were added thereto, after which the reactionmixture was allowed to react at 110° C. for 8 hours and then washed withan aqueous solution of 1 N HCl. The resulting organic layer was driedand purified using silica gel column chromatography, thus obtaining 1.55g (51%) of a compound IIb.

1.55 g of the compound IIb was dissolved in chloroform/methylalcohol(having a volume ratio of 1/3) and then added with 1 g of NaOH, and thereaction mix was stirred for 10 min. The stirred reaction solution waswashed with an aqueous solution of 1 N HCl, and the organic layer wasdried and purified using silica gel column chromatography, thus yielding1.01 g of the derivative IIc.

Analysis of the derivative A material produced the following NMR data:¹H NMR (300 MHz, CDCl₃), δ(ppm) 0.88 (t, 6H, J=6.7 Hz), 1.24-1.45 (m,12H), 1.64-1.69 (m, 4H), 2.77 (t, 4H, J=7.5 Hz), 3.27 (s, 2H), 7.03-7.07(m, 8H).

Preparative Example 6 Synthesis of Example Aromatic Enediyne DerivativeIIIc

3 g (7.5 mmol) of 1,4-dichloro-2,3-diiodobenzene (Chirogenix Co.) and1.5 ml (15.0 mmol) of trimethylsilylacetylene were mixed with a solventof tetrahydrofuran/diisopropylamine (1:1), and 0.15 g (0.23 mmol) ofpalladium dichlorodiphosphine, 21 mg (0.11 mmol) of copper iodide and0.1 g (0.36 mmol) of triphenylphosphine were sequentially added thereto.The reaction solution was heated at 70° C. for 8 hours, and washed withan aqueous solution of ammonium chloride. The resulting organic layerwas dried over magnesium sulfate, dried under reduced pressure, andpurified using silica gel column chromatography, thus obtaining 1.27 gof 1,4-dichloro-2,3-bis(trimethylsilylacetylene)benzene (IIIa).

1.27 g (3.75 mmol) of1,4-dichloro-2,3-bis(trimethylsilylacetylene)benzene, which was thenmixed with 7.5 ml (7.5 mmol) of lithium diisopropylamine (1 M) at about−78° C. The reaction mixture was stirred at the same temperature for 30minutes, then combined with 1.6 ml (7.5 mmol) of dioxaborolane andallowed to react in a bath while the temperature was increased to roomtemperature. The resultant reaction solution was poured into an aqueoussolution of 1 N HCl, treated with chloroform to obtain an organic layer,which was then dried over magnesium sulfate 1 N HCl, treated withchloroform to obtain an organic layer, which was then dried overmagnesium sulfate and distilled under reduced pressure, thus obtaining1.8 g of a compound diborolane in an oil phase.

2.80 g (8.5 mmol) of 2-bromo-2′-hexyl-5,5′-bithiophene and 1.8 g (3.4mmol) of borolane were added to toluene and water, and then aPd(PPh₃)₄[(tetrakis(triphenylphosphine) palladium)(0)(Aldrich)] catalystand potassium carbonate were added thereto, after which the reactionmixture was allowed to react at 110° C. for 8 hours and then washed withan aqueous solution of 1 N HCl. The resulting organic layer was driedand purified using silica gel column chromatography, thus obtaining 1.28g (49%) of a compound IIIb.

1.28 g of the compound IIIb was dissolved in chloroform/methyl alcohol(having a volume ratio of 1/3) and then added with 1 g of NaOH, and thereaction mixture was stirred for 10 min. The stirred reaction solutionwas washed with an aqueous solution of 1 N HCl, and the organic layerwas dried and purified using silica gel column chromatography, thusyielding 0.95 g of the derivative IIIc.

Analysis of the derivative A material produced the following NMR data:1H NMR (300 MHz, CDCl₃), δ(ppm) 0.88 (t, 6H, J=6.5 Hz), 1.23-1.50 (m,20H), 1.64-1.69 (m, 4H), 2.78 (t, 4H, J=7.6 Hz), 3.37 (s, 2H), 7.03-7.08(m, 6H), 7.25, (d, 2H), 7.60 (s, 2H).

Example 1 Fabrication of an Example Organic Semiconductor Thin Film

On a washed plastic substrate, aluminum/niobium (Al/Nb) alloy, servingas a gate electrode, was deposited to a thickness of 1000 Å using asputtering process, and then SiO₂, serving as a gate insulating film,was deposited to a thickness of 1000 Å using a CVD process.

Subsequently, Au, serving as source-drain electrodes, was deposited to athickness of 1200 Å using a sputtering process. Before the substrate wasdeposited with the organic semiconductor material, it was washed usingisopropyl alcohol for 10 min and then dried. The substrate was thenimmersed in a 10 mM solution of octadecyltrichlorosilane in hexane for30 seconds, washed with acetone, and then dried. Example aromaticenediyne derivative A obtained above in Preparative Example 1 wasdissolved at a concentration of 0.1 wt % in a xylene solvent and thenapplied to the prepared substrate using a spin coating process to form acoating film. The coating film was then baked at 150° C. for 30 minutesin an argon atmosphere, thereby manufacturing the bottom-contact-typeorganic thin film transistor generally corresponding to the structureillustrated in FIG. 8.

Examples 2 to 6 Fabrication of Additional Example Organic Thin FilmTransistors

Respective organic thin film transistors were manufactured in the samemanner as detailed above in connection with Example 1, with theexception that each example aromatic enediyne derivatives B, C and Dsynthesized in the corresponding Preparative Examples 2 to 6 was used asthe material for forming the organic active layer.

The organic active layers formed using example aromatic enediynederivatives synthesized in Preparative Examples 1 to 4 were thenmeasured for DSC. The results of these measurements are shown in FIGS. 1to 4.

As shown in FIGS. 1 to 4, each example aromatic enediyne derivative wasfound to begin crosslinking at about 120° C. and then to actively reactat 200° C. or lower. As is apparent from these results, aromaticenediyne derivatives according to example embodiments may besuccessfully converted into a semiconductor thin film using relativelylow-temperature, solution-based wet processes.

The TGA of example aromatic enediyne derivatives obtained in PreparativeExamples 1 and 2 was measured with the results shown in FIGS. 5 and 6.

As reflected in FIGS. 5 and 6, example aromatic enediyne derivativesexhibited no weight loss up to about 300° C. That example aromaticenediyne derivatives did not lose weight even at temperatures exceedingthe reaction temperate of 120 to 160° C. indicates that no more gas wasbeing generated from or in the resulting polymer. Therefore, in the casewhere the semiconductor thin film is formed using aromatic enediynederivatives according to example embodiments, the cracking problem ofthe resulting thin films due to the generation of gas within the filmmay be suppressed or prevented.

In an example organic semiconductor thin film manufactured in Example 1,IR measurements were taken to explore changes in structure of theorganic semiconductor thin film as a function of temperature. Theresults of this evaluation are presented in FIG. 7 and which indicatethat the peaks corresponding to triple bonded carbon (C≡C) and hydrogenbonds associate with a triple bonded carbon (≡C—H) were reduced as theannealing temperature was increased. This result may be attributed tothe formation of benzene rings and the realization of polymerizationaccording to the active mechanism of enediyne when the temperature wasincreased.

In order to evaluate the electrical properties of example organic thinfilm transistors fabricated in Examples 1 to 4, current transferproperties were measured using a semiconductor characterization system(4200-SCS), available from KEITHLEY Co. Ltd., from which charge mobilityand cut-off leakage current were then calculated for each sample. Theresults are given below in TABLE 1. The charge mobility was calculatedusing the above current transfer curve and the following currentequation for the saturation region. That is, the current equation forthe saturation region was converted into a graph relating (I_(SD))^(1/2)to V_(G), and the charge mobility was calculated from the slope of theconverted graph:

$I_{SD} = {\frac{{WC}_{0}}{2L}{\mu\left( {V_{G} - V_{T}} \right)}^{2}}$$\sqrt{I_{SD}} = {\sqrt{\frac{\mu\; C_{0}W}{2L}}\left( {V_{G} - V_{T}} \right)}$${slope} = \sqrt{\frac{\mu\; C_{0}W}{2\; L}}$$\mu_{FET} = {({slope})^{2}\frac{2\; L}{C_{0}W}}$

-   -   wherein I_(SD) is source-drain current; μ or μ_(FET) is charge        mobility; C_(O) is oxide film capacitance; W is channel width; L        is channel length; V_(G) is gate voltage; and V_(T) is threshold        voltage.

The cut-off leakage current (I_(off)), which is the current flowing withthe transistor in the off-state, was determined to be the minimumcurrent in the off-state.

TABLE 1 Organic Active Layer Charge Mobility (cm²/V-s) Cut-off LeakageCurrent (A) Ex. 1 7 × 10⁻⁵ 10⁻¹¹ Ex. 2 5 × 10⁻⁴ 10⁻¹⁰ Ex. 3 8 × 10⁻³ 5 ×10⁻¹¹ Ex. 4 5 × 10⁻⁴ 10⁻¹¹ Ex. 5 6 × 10⁻³ 10⁻¹¹ Ex. 6 8 × 10⁻⁴ 10⁻¹⁰

As is apparent from the data presented in TABLE 1, the transistorsmanufactured using aromatic enediyne derivatives according to exampleembodiments exhibited very low cut-off leakage currents of 10⁻¹⁰ A orless while maintaining the performance thereof. Therefore, when aromaticenediyne derivatives according to example embodiments are applied tovarious electronic devices, for example, thin film transistors,electroluminescent devices, solar cells, and memory, the resultingorganic semiconductor thin film may exhibit improved electricalproperties.

As described above, example embodiments include aromatic enediynederivatives, organic semiconductor thin films formed using such aromaticenediyne derivatives, methods of manufacturing such organicsemiconductor thin films, and methods of manufacturing electronic deviceincorporating such organic semiconductor thin films. Example embodimentsof aromatic enediyne derivatives, which are lower molecular organicsemiconductor materials, may be applied using a wet process at roomtemperature and may be utilized in semiconductor processes requiring theformation of organic semiconductor thin films across large processareas. Moreover, the resulting organic semiconductor thin filmsfabricated from such aromatic enediyne derivatives may exhibit improvedchemical and/or electrical stability as well as a regular moleculararrangement that tends to increase resistance to outgassing andassociated cracking during the thermal processing to form the organicsemiconductor thin films.

Organic semiconductor compounds according to example embodiments may beutilized in various fields including the fabrication of organic thinfilm transistors, electroluminescent devices, solar cells, and memorydevices.

Although example embodiments have been disclosed for illustrativepurposes, those skilled in the art will appreciate that variousmodifications, additions and substitutions are possible, withoutdeparting from the scope and spirit as defined in the following claims.

1. A method of manufacturing an organic semiconductor thin film, comprising: i) applying a precursor solution comprising a minor quantity of an aromatic enediyne derivative having a structure according to Formula I below, and a major quantity of an organic solvent, to a substrate to form a coating film:

wherein X₁, X₂, X₃, A₁, and A₂ are each thiophene; wherein R₁, R₂, R₃ and R₄ are each independently selected from the group consisting of an amino group, a cyano group, —SiR¹R²R³ (where R¹, R², and R³ are each independently selected from a group consisting of hydrogen and C₁-C₁₀ alkyl groups), and C₁-C₂₀ alkyl groups, and further wherein a and b are 1, c is selected from integers from 0 to 2 inclusive, and the expression a+b+c>0 is satisfied; and ii) treating the coating film at a treatment temperature and for a treatment period sufficient to induce crosslinking of the aromatic enediyne derivatives therein, thus forming the organic semiconductor thin film.
 2. The method of forming the organic semiconductor thin film according to claim 1, wherein: applying the precursor solution to the substrate includes a method selected from a group consisting of spin coating, dip coating, roll-to-roll coating, screen coating, spray coating, spin casting, flow coating, screen printing, ink jet coating and drop casting.
 3. The method of forming the organic semiconductor thin film according to claim 1, wherein: the treatment temperature is from 100 to 250° C.
 4. The method of manufacturing the organic semiconductor thin film according to claim 1, wherein: the precursor solution further comprises a minor portion of a second aromatic enediyne derivative selected from a group consisting of aromatic enediyne derivatives having a structure according to Formula II below:

wherein X₁, X₂, X₃, X₄, X₅, and X₆ are each thiophene, R₁, R₂, R₃, R₄, R₅, and R₆ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, and C₁-C₂₀ alkyl groups, and further wherein a, b, c, d, e, and f are independently selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied; and aromatic enediyne derivatives having a structure according to Formula III below:

wherein X₁, X₂, X₃, X₄, X₅, and X₆ are each thiophene, R₁, R₂, R₃, and R₄ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, —SiR¹R²R³ (where R¹, R², and R³ are each independently hydrogen or a C₁-C₁₀ alkyl group), and C₁-C₂₀ alkyl groups, and further wherein a, b, c, d, e and f are selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied.
 5. The method of manufacturing the organic semiconductor thin film according to claim 1, wherein: the precursor solution further comprises a minor portion of a second aromatic enediyne derivative selected from a group consisting of aromatic enediyne derivatives having a structure according to Formula II below:

wherein X₁, X₂, X₃, X₄, X₅, X₆ are each thiophene, R₁, R₂, R₃, R₄, R₅, and R₆ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, and C₁-C₂₀ alkyl groups, and further wherein a b, c, d, e and f are selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied; and a minor portion of a third aromatic enediyne derivative selected from a group consisting of aromatic enediyne derivatives having a structure according to Formula III below:

wherein X₁, X₂, X₃, X₄, X₅, and X₆ are each thiophene, R₁, R₂, R₃, and R₄ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, —SiR¹R²R³ (where R¹, R², and R³ are each independently hydrogen or a C₁-C₁₀ alkyl group), and C₁-C₂₀ alkyl groups; and further wherein a, b, c, d, e and f are selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied.
 6. A method of manufacturing a semiconductor device having an organic semiconductor thin film, comprising: i) applying a precursor solution comprising a minor quantity of an aromatic enediyne derivative having a structure according to Formula I below, and a major quantity of an organic solvent, to a substrate to form a coating film:

wherein X₁, X₂, X₃, A₁, and A₂ are each thiophene; wherein R₁, R₂, R₃ and R₄ are each independently selected from the group consisting of an amino group, a cyano group, —SiR¹R²R³ (where R¹, R², and R³ are each independently selected from a group consisting of hydrogen and C₁-C₁₀ alkyl groups), and C₁-C₂₀ alkyl groups, and further wherein a and b are 1, c is selected from integers from 0 to 2 inclusive, and the expression a+b+c>0 is satisfied; and ii) treating the coating film at a treatment temperature and for a treatment period sufficient to induce crosslinking of the aromatic enediyne derivatives therein, thus forming the organic semiconductor thin film; and iii) configuring the organic semiconductor thin film to serve as a carrier transport layer.
 7. The method of manufacturing a semiconductor device having an organic semiconductor thin film according to claim 6, wherein: the precursor solution further comprises a minor portion of a second aromatic enediyne derivative selected from a group consisting of aromatic enediyne derivatives having a structure according to Formula II below:

wherein X₁, X₂, X₃, X₄, X₅, X₆ are each thiophene, R₁, R₂, R₃, R₄, R₅, and R₆ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, and C₁-C₂₀ alkyl groups, and further wherein a b, c, d, e and f are selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied; and aromatic enediyne derivatives having a structure according to Formula III below:

wherein X₁, X₂, X₃, X₄, X₅, and X₆ are each thiophene, R₁, R₂, R₃, and R₄ are each independently selected from the group consisting of hydrogen, an amino group, a cyano group, —SiR¹R²R³ (where R¹, R², and R³ are each independently hydrogen or a C₁-C₁₀ alkyl group), and C₁-C₂₀ alkyl groups; and further wherein a, b, c, d, e and f are selected from integers from 0 to 1 inclusive, and the expression 3≦a+b+c+d+e+f≦5 is satisfied.
 8. The method of manufacturing a semiconductor device having an organic semiconductor thin film according to claim 6, wherein: configuring the organic semiconductor thin film to serve as a carrier transport layer further comprises forming the organic semiconductor layer film on a gate dielectric layer.
 9. The method of manufacturing a semiconductor device having an organic semiconductor thin film according to claim 6, wherein: the semiconductor device is selected from a group consisting of thin film transistors, electroluminescent devices, display devices, solar cells and memory devices. 